1. Field of the Invention
The present invention relates to a photoelectron emitting member providing a photoelectron effect.
Fine particles electrically charged with photoelectrons can be used in various applications such as (a) separation and classification of fine particles, as well as modifying their surfaces and controlling an electrically charged amount thereof; (b) the measurement of the concentration and size of fine particles in gases such as air and waste gases by using electrically charged fine particles; and (c) trapping and removal of charged fine particles to produce clean gases.
2. Description of the Prior Art
The present inventor has previously proposed many methods of electrically charging fine particles with photoelectrons that are emitted upon applying uv rays and/or other forms of radiation to a photoelectron emitting member and various applications of the thus formed photoelectron emitting member.
In the method of producing clean gases proposed by the present inventor, the following is particularly relevant to the present invention: Japanese Patent Public Disclosure (Laid-Open) Nos. 178050/1986 (corresponding to U.S. Pat. No. 4,750,917), 244459/1987, 77557/1988, 100955/1988 and 262954/1989.
With regard to the measurements, the following is proposed by the inventor: Japanese Patent Public Disclosure (Laid-Open) Nos. 242838/1987 and 47536/1990, and Japanese Patent Application No. 134781/1989.
With regard to the separation and classification, the following is proposed by the inventor: Japanese Patent Application No. 177198/1989.
Further, with regard to the conditions of electrically charging fine particles, the following is proposed by the inventor: Japanese Patent Application Nos. 120563/1989 and 120564/1989.
However, the conventional photoelectron emitting members were in a bulk-like (lump-like) form. Said members were limited in the amount of emitting photoelectrons they emitted and in the stability thereof, so there has been a need to modify such materials to provide for their improvement. The materials having a small work function which are capable of effective emission of photoelectrons are liable to deterioration and lack stability during prolonged operation.